Forum Discussion
NimbostratusLoad balancing Exchange CAS traffic from single source(s)
Hello,
Is there a way to effectively load balance traffic from single sources across multiple Exchange 2010 CAS servers? We have 3 CAS servers, but the bulk of the OWA traffic is coming from a single source IP (a Juniper gateway), and the bulk of the activesync traffic is coming from the Blackberry server. Consequently we have 1 CAS box running near 100% cpu from OWA, one running near 100% from activesync, and a 3rd CAS box basically idling.
Is there a way to get F5 LTM to spread this traffic around more effectively without breaking Exchange?
Thanks for any tips
6 Replies
Hello-
The "clumping" you're seeing only happens if you do persistence (Microsoft calls this "affinity") based on source IP address.
F5's Deployment Guide for Exchange Server 2010 and 2013 is available at http://www.f5.com/pdf/deployment-guides/microsoft-exchange-2010-2013-iapp-dg.pdf
In that guide, we recommend "cookie" persistence for OWA traffic, and persisting on the Authorization header for ActiveSync. Neither method would exhibit the behavior you're seeing.
If you use F5's iApp for CAS (see more info here: https://support.f5.com/kb/en-us/solutions/public/13000/400/sol13497.html?sr=35799426), the correct persistence types will be set up automatically.
Please let us know if that helps with the issue you're seeing!
-Dayne
nbhms_37291The Exchange iApp was used for the F5 LTM deployment. Is it the iRules I should be looking at to see the persistence? I looked at the iRules, and they seemed to be following what you mentioned, with fallback to source address. As far as I know none of the iApp defaults were changed after deployment.
The SNAT Pool also has a persistence setting of cookie first with fallback to source IP.
What version of the iApp did you use? The only suggested version right now is the downloadable version 1.2. Earlier versions, including those that shipped with any version of BIG-IP, are no longer suggested.
Also, do you have a case open with F5 Support? If so, we can take a look at your configuration.
- nbhms_37291
I did notice today there was a newer iApp template out, and did see there was a mention of a cookie persistence bug fix in the readme notes. I think we're at the iApp one rev back, 2012-04-06 or something like that.
Have not opened a case yet, thought I'd check here first and see if we were missing anything obvious.
If you're at 2012_04_06, you're actually two revisions back; that was superseded by 2012_06_08 and subsequently by version 1.2 (we switched numbering schemes).
If at all possible, please install and upgrade to a newer version; alternately, deploy using the new version on a separate IP address and test some clients using an entry in the local 'hosts' file or something similar. When you're satisfied that the new version works according to your plan, you can either swap IP addresses or change DNS entries to point to the new IP address(es).
Please open a support case if you run into any difficulties, this does not resolve the situation you're seeing, or you simply want assistance in installing and using the new iApp. (However, the Deployment Guide is fairly detailed on how to use it.)
scsp_177450Hi, Do you have any luck with this? I am looking at a similar situation. Cheers!
